Consolidation - Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Cash and cash equivalents		$ 221,781
Noncontrolling interests	$ (115,513)	(63,845)	$ (57,481)	$ (4,178)
VOEs
Variable Interest Entity [Line Items]
Cash and cash equivalents	9,837	2,665
Investments	57,256	22,223
Other assets	1,989	1,563
Notes payable	0	0
Securities purchased payable and other liabilities	(2,566)	(2,964)
Noncontrolling interests	(24,707)	(3,865)
Net interests in CIP	41,809	19,622
CLOs
Variable Interest Entity [Line Items]
Cash and cash equivalents	82,295	97,130
Investments	2,217,055	1,976,148
Other assets	10,484	21,450
Notes payable	(2,190,445)	(1,834,535)
Securities purchased payable and other liabilities	(42,940)	(164,887)
Noncontrolling interests	(9,799)	(10,558)
Net interests in CIP	66,650	84,748
Other
Variable Interest Entity [Line Items]
Cash and cash equivalents	1,206	363
Investments	58,966	31,739
Other assets	957	599
Notes payable	0	0
Securities purchased payable and other liabilities	(323)	(200)
Noncontrolling interests	(3,354)	(1,564)
Net interests in CIP	$ 57,452	$ 30,937